Top­ping an LMM with Wa­gler cylin­der heads

Ultimate Diesel Builder's Guide - - Contents - Text / Pho­tog­ra­phy: Chris Tobin

In the gasser com­mu­nity, bolt­ing on a set of af­ter­mar­ket cylin­der heads is a great way to boost the per­for­mance of an en­gine, but on the diesel side of the fence there are not many af­ter­mar­ket op­tions. Wa­gler Com­pe­ti­tion Prod­ucts de­signed re­place­ment heads for Duramax en­gines that of­fer greatly im­proved air­flow while bolt­ing on just like a fac­tory head. The heads are avail­able in many con­fig­u­ra­tions from ba­sic stock re­place­ments to wild Cnc-ported and hand-blended units with over­size valves, cus­tom springs and ti­ta­nium re­tain­ers.

Here, we’ll show you the in­stal­la­tion of a pair of Wa­gler “As-cast” heads on a 2009 GMC Sierra 2500 HD with an LMM en­gine un­der the hood. We vis­ited WCP’S shop in Odon, In­di­ana, and fol­lowed along to doc­u­ment the process as Jeremy Wa­gler per­formed the in­stal­la­tion on Grant Adams’ GMC.

While Wa­gler was tear­ing into the Duramax en­gine, Adams de­cided he should make a few more up­grades at the same time—namely in­stalling ARP head studs, Comp Cams bee­hive valve springs, 30% over in­jec­tors from S&S Diesel Mo­tor­sport and forged WCP push rods. The en­gine could have been put back to­gether us­ing the stock com­po­nents, but it’s much eas­ier to up­grade and re­place these items while the heads are off than to do it later. In ad­di­tion to the up­graded com­po­nents, a new gas­ket kit for the Duramax’s top end was nec­es­sary. Wa­gler prefers to use GM head gas­kets and a Mahle gas­ket kit for the rest. A word to the wise: Never re­use head gas­kets as they will al­most cer­tainly leak and cause more headaches.

Adams chose to re­use his ex­ist­ing valves in the new WCP heads to save money. Since the stock clamshell in­take man­i­folds were be­ing re­tained, he opted to have WCP per­form their clamshell-re­lief CNC ma­chin­ing on the in­take side of the heads. This im­proves in­take air­flow through the re­stric­tive fac­tory in­take man­i­folds. Wa­gler in­stalled an LML man­i­fold on the driver’s side of the LMM to help im­prove ex­haust flow. This elim­i­nates the pinch point that’s de­signed into the LMM ex­haust man­i­folds with­out go­ing to the ex­pense of us­ing af­ter­mar­ket man­i­folds and up-pipes.

For im­proved fuel de­liv­ery, the crew at S&S starts with new Bosch in­jec­tors and then me­dia hones the noz­zles in-house to in­crease the flow in their 30% over in­jec­tors. For the larger in­jec­tors, they use their elec­tric dis­charge ma­chin­ing (EDM) to in­crease the noz­zle bore and ad­just

the an­gles be­fore they’re me­dia honed. All of their in­jec­tor sets are run on the flow bench to match and bal­ance the set for op­ti­mum per­for­mance.

As you would ex­pect, in­stalling a pair of cylin­der heads on a truck is an ex­ten­sive process. We’ll just give you an over­view here. A head swap can be done in your garage or drive­way in a few days if you have the DIY skills to han­dle it. As we al­ways say, if it’s be­yond your abil­i­ties, it is best to have your lo­cal diesel per­for­mance specialist han­dle the in­stal­la­tion for you. Al­ways be sure to prac­tice safe shop tech­niques if you do the work your­self.

When the in­stal­la­tion was com­pleted, Wa­gler took the truck up to Danville Per­for­mance for an­other dyno ses­sion and EFILIVE tun­ing by Mark Broviak. He ran Adams’ truck on the dyno in stock trim be­fore the head in­stal­la­tion and it put 351 horse­power and 642 lb-ft of torque to the rear wheels as a base­line. Then, with just the heads and in­jec­tors but no tun­ing changes, peak horse­power jumped up to 406 and torque peaked at 728 lb-ft.

Af­ter the ini­tial suc­cess with no tun­ing, Broviak went to work cre­at­ing EFILIVE tun­ing files that would work well with the ad­di­tional

air­flow and fuel that the LMM now had avail­able. He found that he was able to tune the truck with less tim­ing and in­jec­tion du­ra­tion than is typ­i­cal for Duramax trucks with stock heads, which leads us to think that the truck will yield bet­ter fuel econ­omy un­der nor­mal driv­ing sit­u­a­tions. The less ag­gres­sive tun­ing is also much eas­ier on the en­gine, mean­ing that for the same power out­put, Adams’ Duramax is not stressed as hard as one run­ning more ag­gres­sive tun­ing to reach a given power level. You can see on the dyno graph that the truck made quite a bit more power and a lot more torque with the Danville Per­for­mance cus­tom tun­ing.

The horse­power out­put ranged from 400 up to 533, while the torque ranged from 758 to 1,138 lb-ft with the new tun­ing, giv­ing the truck a to­tal peak im­prove­ment of 182 horse­power and 496 lb-ft of torque over the stock con­fig­u­ra­tion. In ad­di­tion to the peak power and torque gains, we can see that the ad­di­tional air and fuel helped give the power band a sig­nif­i­cant bump, start­ing at about 2,300 rpm where you’ll re­ally feel it in the seat of your pants. Broviak no­ticed on the big tune that the truck was hav­ing trou­ble main­tain­ing rail

pres­sure to the in­jec­tors so he backed out of the throt­tle at around 3,300 rpm as seen on the pink traces. He felt that a lift pump would help the CP3 keep up bet­ter and help make pos­si­bly as much as 600 hp.

We took the truck out for a test drive af­ter Broviak com­pleted his dyno tun­ing ses­sion. The throt­tle re­sponse was re­mark­able and the stock turbo spooled ef­fort­lessly, mak­ing plenty of power to break the rear tires loose on de­mand at just about any speed. Idle and steady state driv­ing was no dif­fer­ent than with the stock truck, but the truck launched ahead with au­thor­ity when we mashed the skinny pedal. We’ve seen sim­i­lar power lev­els from Duramax trucks with tun­ing and in­jec­tor up­grades like this one, but the im­prove­ments in throt­tle re­sponse and relaxed tun­ing are at­trib­uted to the im­proved air­flow from the Wa­gler cylin­der heads. Adams’ LMM is also very clean, with very lit­tle smoke, even dur­ing full-throt­tle blasts in the hot tune.

You can fol­low the pro­ce­dure on these pages for an over­view of the Wa­gler Com­pe­ti­tion Prod­ucts Duramax cylin­der head in­stal­la­tion. If you would like more de­tails on the heads and what makes them spe­cial, point your browser

to Wa­gler­com­pe­ti­tion.com. The heads make a sig­nif­i­cant im­prove­ment in per­for­mance and driv­abil­ity on a truck with mild in­jec­tor and tun­ing up­grades like Adams’ GMC. He re­ported back to Wa­gler that the truck is much more re­spon­sive, es­pe­cially when tow­ing heavy loads, and that he has seen a two- to three-mpg im­prove­ment in fuel econ­omy.

For those of you want­ing to get ev­ery last bit of per­for­mance out of your Duramax for com­pe­ti­tion use with big in­jec­tors, a big cam and a big turbo (or tur­bos), you’ll be able to fully re­al­ize the po­ten­tial of your other up­grades with a set of WCP heads on your Duramax. Just re­mem­ber to tell them that your friends at UDBG re­ferred you. UBDG

16 Fol­low­ing ARP'S in­stal­la­tion in­struc­tions, Wa­gler brings the head studs up to their fi­nal torque value in three se­quen­tial steps as di­rected. 17 When in­stalling the val­ve­train com­po­nents, Wa­gler uses gen­er­ous amounts of Cle­vite as­sem­bly lube to...

21 Af­ter the in­jec­tors are in­stalled and torqued, Wa­gler cleaned and in­stalled the fuel rails and fuel lines.

20 When in­stalling the in­jec­tors, don’t for­get to in­stall the cop­per washer over the in­jec­tor noz­zle to seal the in­jec­tor in the head.

18 Af­ter the rocker arms are in­stalled, do not for­get to set the valve lash. If you don't, you could dam­age your en­gine by leav­ing the valves open too much or not enough.

19 Wa­gler lu­bri­cates the O-rings on the S&S Diesel Mo­tor­sport in­jec­tors be­fore in­stalling them in the cylin­der heads.

22 To help pre­vent dam­age to the in­take bridge seals, Wa­gler coats them with a multi-pur­pose grease so that they slide down the clamshells and won't snag or bunch up the seals.

12 In the WCP clean room, Wa­gler in­stalled Adams' valves into the new heads with new Comp Cams bee­hive valve springs.

14 Be­fore in­stalling the head gas­kets, Wa­gler cleans the sur­face of the block with a ra­zor and then lightly sands it with a block and fine wet/dry paper. He then sprays it down with brake cleaner and fi­nally wipes the sur­face down with a tack-cloth to...

10 Adams de­cided to re­use the valves from his fac­tory heads to save some money, so Wa­gler cleaned them and trans­ferred them over to the new heads. 11 It’s time to get the light car­bon buildup off with a wire wheel.

9 Wa­gler fi­nally lifts the heads off the en­gine to make room for the new WCP heads. On the pas­sen­ger-side head, the ex­haust man­i­fold will need to be re­moved from the head since the dip­stick tube runs be­tween the head and the man­i­fold. 15 Af­ter the...

13 Af­ter the clamshell in­take man­i­folds are in­stalled on the head, you can see that the CNC re­lief cut into the head matches the in­take. This will in­crease flow by al­low­ing air a smoother en­try to the in­take ports.

9 Wa­gler fi­nally lifts the heads off the en­gine to make room for the new WCP heads. On the pas­sen­ger-side head, the ex­haust man­i­fold will need to be re­moved from the head since the dip­stick tube runs be­tween the head and the man­i­fold. 15 Af­ter the...

8 There’s not enough room to com­pletely re­move the driver-side rear head bolt, so af­ter loos­en­ing the bolt, hold it up with a clothes­pin to keep it from get­ting hung up while re­mov­ing the head. Then re­use the clothes­pin when in­stalling the head with...

6 Af­ter you dig down to the fuel sys­tem, you can re­move the fuel rails and high-pres­sure fuel lines (be sure to set them down in the or­der you re­move them to make it eas­ier to re­in­stall them when putting the truck back to­gether). The orig­i­nal fuel...

5 The elec­tri­cal har­nesses for the en­gine also need to be un­plugged and moved off to the side to get down to the cylin­der heads. Take care if you’re do­ing this at home, as the plug con­nec­tor clips can be­come brit­tle due to en­gine heat. You don’t want...

3 While the A/C sys­tem is evac­u­ated and the coolant drains, Wa­gler re­moves the bumper, grille and as­so­ci­ated front-end brack­ets be­fore re­mov­ing the ra­di­a­tor and in­ter­cooler to­gether as a unit.

4 Of course, it was nec­es­sary to re­move the fan and all of the front­drive ac­ces­sories and brack­ets to get down to the front of the en­gine block.

24 Since the oil is likely con­tam­i­nated with brake cleaner from the deck sur­face clean­ing process, Wa­gler al­ways drains the old oil, changes the fil­ter and re­fills with high-qual­ity diesel-spe­cific oil such as the Petro-canada Duron-e he uses in all...

25 Once ev­ery­thing is put back to­gether, no one will know the power you have un­leashed deep in­side the heart of your en­gine bay, mak­ing it great for that sleeper ap­proach at the track. 28 Here’s the dyno chart with the hard num­bers show­ing power gains.

26 Mark Broviak at Danville Per­for­mance wrote cus­tom EFILIVE tunes for Adams' LMM to op­ti­mize per­for­mance with the cylin­der head and fuel in­jec­tor up­grades.

23 Re­in­stalling the en­gine com­po­nents is the re­verse of re­moval process, and if you kept ev­ery­thing or­ga­nized as you took it off, it will go as smoothly as it did for Wa­gler.

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